A revised proposal is submitted to provide an apprenticeship in molecular biology for the candidate, who is a board-eligible Clinical Oncologist. The candidate was initially exposed to basic research during her clinical oncology training at Fox Chase Cancer Center and for the past year and a half has been engaged in full-time laboratory instruction in the field of transcriptional regulation. Her performance in clinical hematology and oncology, as well as her continued commitment to basic research, are documented in the proposal. The sponsor, John B. E. Burch, Ph.D., is a tenured member of Fox Chase Cancer Center and is a Member of the Graduate Group in Medical Biology and an Adjunct Associate Professor of Human Genetics at the University of Pennsylvania. He has trained both M.D. and Ph.D. Postdoctoral Fellows and his research program is supported through 1997 by an NIH RO1 grant, that was initially awarded in 1984. The sponsor has made significant contributions in two-fields of relevance to neoplasia; namely, retrotransposable elements and transcriptional regulation. The setting is Fox Chase Cancer Center, a comprehensive Cancer Center internationally known for its clinical and basic research. The training plan includes both a didactic program of instruction and an independent research project. The didactic training will include a textbook review of molecular biology, a weekly Journal club, a weekly Postdoctoral Training Course and yearly participation at major conferences on transcriptional regulation and cancer research. New comprehensive technical training will be acquired by executing an integrated set of experiments that have been designed to reveal the complete structure of chicken CR1 non-LTR retrotransposons and to determine the parameters that govern the retrotransposition of these elements. CR1 elements constitute only the third example of a vertebrate non-LTR retrotransposon family with a pol- like (reverse transcriptase) open reading frame. Moreover, CR1 elements are unique among all non-LTR retrotransposons with respect to the sequences that are present at the 3' ends of the retrotransposed copies, which suggests that they may use a novel strategy to prime their reverse transcription. The unusually high frequency of 5' truncations for retrotransposed CR1 elements will be exploited to isolate all of the potentially functional CR1 non-LTR retrotransposons. The issue as to whether external or internal promoters are used to transcribe the potentially functional CR1 non-LTR retrotransposons and the issue as to whether these elements can retrotranspose will be tested. These studies should provide evidence either for CR1 elements being self-propagating or for newly integrated elements being derived from a small number of master CR1 elements. The fact that CR1-like elements also exist in species from two non-avian vertebrate classes underscores the enormous impact that the retrotransposition of these elements has had to the mutation and evolution of diverse genomes. The proposed training program will provide the candidate with a solid foundation in molecular biology that should enable her to pursue an independent academic career in experimental oncology.